Proteins involved in nerve excitation were studied using two main approaches. In one approach the nature of the interactions between excitable sites and the underlying cytoskeletal proteins was studied. Using intracellularly perfused squid giant axons, it was found that application of tetrodotoxin or saxitoxin to the nerve cause a release of cytoskeletal proteins into the perfusion solution. The other approach used embryonic chick skeletal muscle to study the development of the exictable sites in muscle. The excitable sites were studied using a number of neurotoxins known to bind to these sites, including saxitoxin, tetrodotoxin, scorpion toxin, veratridine and batrachotoxin.